U.S. patent number 10,947,880 [Application Number 16/261,115] was granted by the patent office on 2021-03-16 for injector for reductant delivery unit having fluid volume reduction assembly.
This patent grant is currently assigned to Continental Powertrain USA, LLC. The grantee listed for this patent is Continental Powertrain USA, LLC. Invention is credited to Stephen C Bugos, Joshua Lee Hatfield, Keith Aaron Shaw.
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United States Patent |
10,947,880 |
Hatfield , et al. |
March 16, 2021 |
Injector for reductant delivery unit having fluid volume reduction
assembly
Abstract
A fluid injector includes a calibration filter tube including a
bore defined in an axial direction through the calibration filter
tube, the bore defining at least a portion of a fluid path through
the fluid injector, the calibration filter tube including a
plurality of holes which extend from the bore to an outer surface
of the calibration filter tube. A volume reduction member has a
bore though which the calibration filter tube extends, the volume
reduction member occupying a space between the outer surface of the
calibration filter tube and an inner surface of the tube member,
the volume reduction member being constructed from resilient,
compressible material. Freezing or frozen fluid disposed in the
calibration filter tube expands through the holes and at least
partially compresses the volume reduction member, so as to reduce
fluid expansion forces damaging other components of the fluid
injector.
Inventors: |
Hatfield; Joshua Lee (Newport
News, VA), Shaw; Keith Aaron (Yorktown, VA), Bugos;
Stephen C (Poquoson, VA) |
Applicant: |
Name |
City |
State |
Country |
Type |
Continental Powertrain USA, LLC |
Auburn Hills |
MI |
US |
|
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Assignee: |
Continental Powertrain USA, LLC
(Auburn Hills, MI)
|
Family
ID: |
1000005423906 |
Appl.
No.: |
16/261,115 |
Filed: |
January 29, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20190234274 A1 |
Aug 1, 2019 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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62625317 |
Feb 1, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01N
3/2066 (20130101); F01N 2610/02 (20130101); F01N
2610/1486 (20130101); F01N 2610/1453 (20130101) |
Current International
Class: |
F01N
3/20 (20060101) |
Field of
Search: |
;239/548 |
References Cited
[Referenced By]
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Other References
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Co.,
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-alloys/marvac-125/marvac-125-mechanische-eigenschaften-band.html);
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|
Primary Examiner: Greenlund; Joshua A
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
The present application claims the benefit of U.S. provisional
application 62/625,317, filed Feb. 1, 2018, and entitled "INJECTOR
FOR REDUCTANT DELIVERY UNIT HAVING FLUID VOLUME REDUCTION
ASSEMBLY," the content of which is hereby incorporated by reference
herein in its entirety.
Claims
What is claimed is:
1. A reductant delivery unit, comprising: a fluid injector having a
fluid inlet disposed at a first end of the fluid injector for
receiving a reductant, and a fluid outlet disposed at a second end
of the fluid injector for discharging the reductant, the fluid
injector defining a fluid path for the reductant from the fluid
inlet to the fluid outlet, the fluid injector comprising: a tube
member having an end disposed at the fluid inlet of the fluid
injector, the tube member configured to pass reductant along the
fluid path; a calibration filter tube disposed in the tube, the
calibration filter tube having a first end portion and a second
end, and further including a bore defined in an axial direction
through the calibration filter tube, the bore defining at least a
portion of the fluid path through the fluid injector; an actuator
unit disposed within the fluid injector downstream of the
calibration filter tube, the actuator unit engaging the second end
of the calibration filter tube; a valve assembly operatively
coupled to the actuator unit, wherein a position of the calibration
filter tube within the tube member at least partly sets an opposing
opening force for the valve assembly; and a volume reduction member
having a bore though which the calibration filter tube extends, the
volume reduction member occupying a space between an outer surface
of the calibration filter tube and an inner surface of the tube
member, wherein the outer surface of the calibration filter tube is
an outer radial surface of the calibration filter tube which
extends between axial end surfaces of the calibration filter tube,
wherein the calibration filter tube includes one or more apertures
extending between the bore of the calibration filter tube in a
radial direction between the bore of the calibration filter tube
and the outer surface thereof.
2. The reductant delivery unit of claim 1, wherein the volume
reduction member is formed from a resilient, compressible
material.
3. The reductant delivery unit of claim 2, wherein the resilient,
compressible material comprises one of a rubber composition and
closed cell foam.
4. The reductant delivery unit of claim 1, wherein the fluid
injector further comprises a filter and a cap member including a
sidewall defining an inner space into which the filter is disposed,
the sidewall contacting the first end of the calibration filter
tube.
5. The reductant delivery unit of claim 1, wherein the one or more
apertures of the calibration filter tube is adjacent the volume
reduction member such that freezing or frozen reductant disposed in
the calibration filter tube expands through the holes and at least
partially compresses the volume reduction member.
6. The reductant delivery unit of claim 5, wherein melting
reductant allows for the volume reduction member to expand so as to
be adjacent the holes of the calibration filter tube.
7. A fluid injector, comprising: a fluid inlet disposed at a first
end and configured to receive a fluid, and a fluid outlet disposed
at a second end of the fluid injector for discharging the fluid,
the fluid injector defining a fluid path for the fluid from the
fluid inlet to the fluid outlet; a tube member having an end
disposed at the fluid inlet of the fluid injector, the tube member
configured to pass fluid along the fluid path; a filter disposed in
the tube member proximal to the fluid inlet of the fluid injector;
a calibration filter tube disposed in the tube member, the
calibration filter tube having a first end portion and a second
end, and further including a bore defined in an axial direction
through the calibration filter tube, the bore defining at least a
portion of the fluid path through the fluid injector, the
calibration filter tube including a plurality of holes which extend
from the bore to an outer surface of the calibration filter tube;
wherein the outer surface of the calibration filter tube is an
outer radial surface of the calibration filter tube which extends
between axial end surfaces of the calibration filter tube, wherein
the plurality of holes extend in a radial direction between the
bore of the calibration filter tube and the outer surface thereof,
a volume reduction member having a bore though which the
calibration filter tube extends, the volume reduction member
occupying a space between the outer surface of the calibration
filter tube and an inner surface of the tube member, the volume
reduction member being constructed from resilient, compressible
material; an actuator unit disposed within the fluid injector
downstream of the calibration filter tube, the actuator unit
engaging the second end of the calibration filter tube; and a valve
assembly operatively coupled to the actuator unit, wherein a
position of the calibration filter tube within the tube member sets
an opposing opening force of the valve assembly.
8. The fluid injector of claim 7, wherein volume reduction member
is constructed from one of a rubber composition and a closed cell
foam.
9. The fluid injector of claim 7, wherein the fluid injector
comprises an RDU injector.
10. The fluid injector of claim 7, wherein freezing or frozen fluid
disposed in the calibration filter tube expands through the holes
and at least partially compresses the volume reduction member.
Description
FIELD OF INVENTION
The present invention generally relates to a fluid injector of a
reductant delivery unit (RDU), and particularly to a robust RDU
fluid injector for non-purge applications.
BACKGROUND
Emissions regulations in Europe and North America are driving the
implementation of new exhaust aftertreatment systems, particularly
for lean-burn technologies such as compression-ignition (diesel)
engines, and stratified-charge spark-ignited engines (usually with
direct injection) that are operating under lean and ultra-lean
conditions. Lean-burn engines exhibit high levels of nitrogen oxide
emissions (NOx) that are difficult to treat in oxygen-rich exhaust
environments characteristic of lean-burn combustion. Exhaust
aftertreatment technologies are currently being developed that
treat NOx under these conditions.
One of these technologies includes a catalyst that facilitates the
reactions of ammonia (NH.sub.3) with the exhaust nitrogen oxides
(NOx) to produce nitrogen (N.sub.2) and water (H.sub.2O). This
technology is referred to as Selective Catalytic Reduction (SCR).
Ammonia is difficult to handle in its pure form in the automotive
environment, therefore it is customary with these systems to use a
diesel exhaust fluid (DEF) and/or liquid aqueous urea solution,
typically at a 32% concentration of urea (CO(NH.sub.2).sub.2). The
solution is referred to as AUS-32, and is also known under its
commercial name of AdBlue. The reductant solution is delivered to
the hot exhaust stream typically through the use of an injector,
and is transformed into ammonia prior to entry in the catalyst.
More specifically, the solution is delivered to the hot exhaust
stream and is transformed into ammonia in the exhaust after
undergoing thermolysis, or thermal decomposition, into ammonia and
isocyanic acid (HNCO). The isocyanic acid then undergoes a
hydrolysis with the water present in the exhaust and is transformed
into ammonia and carbon dioxide (CO.sub.2), the ammonia resulting
from the thermolysis and the hydrolysis then undergoes a catalyzed
reaction with the nitrogen oxides as described previously.
AUS-32, or AdBlue, has a freezing point of -11 C, and system
freezing is expected to occur in cold climates. Since these fluids
are aqueous, volume expansion happens after the transition to the
solid state upon freezing. The expanding solid can exert
significant forces on any enclosed volumes, such as an injector.
This expansion may cause damage to the injection unit, so different
SCR strategies exist for addressing reductant expansion.
There are two known SCR system strategies in the marketplace: purge
systems and non-purge systems. In purge SCR systems, the reductant
urea and/or DEF solution is purged from the RDU when the vehicle
engine is turned off. In non-purge SCR systems, the reductant
remains in the RDUs throughout the life of the vehicle. During
normal operation of a non-purge SCR system, the RDU injector
operates at temperatures which are above the freezing point of the
reductant such that reductant in the RDU remains in the liquid
state. When the vehicle engine is turned off in the non-purge SCR
system, however, the RDU injector remains filled with reductant,
thereby making the RDU injector susceptible to damage from
reductant expanding in freezing conditions.
SUMMARY
Example embodiments overcome shortcomings found in existing RDU
fluid injectors and provide an improved fluid injector for
non-purge SCR systems in which the adverse effects from the RDU
being in temperatures that are below the freezing point of
reductant are reduced.
In an example embodiment, an RDU includes a fluid injector having a
fluid inlet disposed at a first end of the fluid injector for
receiving a reductant, and a fluid outlet disposed at a second end
of the fluid injector for discharging the reductant, the fluid
injector defining a fluid path for the reductant from the fluid
inlet to the fluid outlet. The fluid injector includes a tube
member having an end disposed at or near the fluid inlet of the
fluid injector, the tube member configured to pass reductant along
the fluid path; a calibration filter tube disposed in the tube, the
calibration filter tube having a first end portion adjacent the
filter and a second end, and further including a bore defined in an
axial direction through the calibration filter tube, the bore
defining at least a portion of the fluid path through the fluid
injector; an actuator unit disposed within the fluid injector
downstream of the calibration filter tube, the actuator unit
engaging the second end of the calibration filter tube; a valve
assembly operatively coupled to the actuator unit, wherein a
position of the calibration filter tube within the tube member at
least partly sets an opposing opening force for the valve assembly;
and a volume reduction member having a bore though which the
calibration filter tube extends, the volume reduction member
occupying a space between an outer surface of the calibration
filter tube and an inner surface of the tube member. The
calibration filter tube includes one or more apertures extending
between the bore of the calibration filter tube and the outer
surface thereof.
The volume reduction member is formed from a resilient,
compressible material. The resilient, compressible material
includes one of a rubber composition and closed cell foam.
The fluid injector further includes a filter and a cap member
including a sidewall defining an inner space into which the filter
is disposed, the sidewall contacting the first end of the
calibration filter tube.
The one or more holes of the calibration filter tube is adjacent
the volume reduction member such that freezing or frozen reductant
disposed in the calibration filter tube expands through the holes
and at least partially compresses the volume reduction member.
Melting reductant allows for the volume reduction member to expand
so as to be adjacent the holes of the calibration filter tube.
BRIEF DESCRIPTION OF THE DRAWINGS
Aspects of the invention will be explained in detail below with
reference to an exemplary embodiment in conjunction with the
drawings, in which:
FIG. 1 is a cross-sectional side view of an RDU for a non-purge SCR
system according to an example embodiment;
FIG. 2 is a cross-sectional side view of a fluid injector of the
RDU of FIG. 1;
FIG. 3 is a magnified cross-sectional view of the inlet portion of
the fluid injector of the RDU of FIG. 1 according to an example
embodiment;
FIG. 4 is an exploded perspective view of components of the fluid
injector of the RDU of FIG. 1 according to an example
embodiment;
FIG. 5 is a magnified cross-sectional view of the outlet portion of
the fluid injector of the RDU of FIG. 1 according to an example
embodiment;
FIG. 6 is a magnified cross-sectional view of the inlet portion of
the fluid injector of the RDU of FIG. 1 according to another
example embodiment;
FIG. 7 is an exploded perspective view of components of the fluid
injector of FIG. 6;
FIG. 8 is a cross-sectional view of the components of FIG. 6;
FIG. 9 is a magnified cross-sectional view of the inlet portion of
the fluid injector of the RDU of FIG. 1 according to yet another
example embodiment;
FIG. 10 is a cross-sectional view of components of the fluid
injector of FIG. 9;
FIG. 11 is a perspective view of a component of the fluid injector
of FIG. 9;
FIG. 12 is a cross-sectional view of the inlet portion of the fluid
injector of the RDU of FIG. 1 according to another example
embodiment;
FIG. 13 is a cross-sectional view of integrated components of the
fluid injector of FIG. 12;
FIG. 14 is an exploded perspective view of the components of the
fluid injector of FIG. 13;
FIG. 15 is a cross-sectional view of the inlet portion of the fluid
injector of the RDU of FIG. 1 according to another example
embodiment;
FIG. 16 is a cross-sectional view of integrated components of the
fluid injector of FIG. 15;
FIG. 17 is an exploded perspective view of the components of the
fluid injector of FIG. 15;
FIG. 18 is a cross-sectional view of a fluid injector of the RDU of
FIG. 1, according to another example embodiment;
FIG. 19 is a cross-sectional view of a portion of the fluid
injector of FIG. 18 according to an example embodiment;
FIGS. 20 and 21 are cross-sectional views of a portion of the fluid
injector of FIG. 18 according to another example embodiment;
and
FIG. 22 is an exploded perspective view of a portion of the fluid
injector of FIG. 18 according to another example embodiment.
DETAILED DESCRIPTION
The following description of the example embodiment(s) is merely
exemplary in nature and is in no way intended to limit the
invention, its application, or uses.
Example embodiments are generally directed to an RDU for a
non-purge SCR system in which damaging effects from a reductant,
DEF and/or urea solution freezing in the RDU injector are
reduced.
FIG. 1 illustrates an RDU 10 of a non-purge SCR system according to
an example embodiment. RDU 10 includes a solenoid fluid injector,
generally indicated at 12, that provides a metering function of
fluid and provides the spray preparation of the fluid into the
exhaust path of a vehicle in a dosing application. Thus, fluid
injector 12 is constructed and arranged to be associated with an
exhaust gas flow path upstream of a selective catalytic reduction
(SCR) catalytic converter (not shown). Fluid injector 12 may be an
electrically operated, solenoid fuel injector. As shown in FIGS. 1
and 2, fluid injector 12 includes an actuator unit having a coil 14
and a movable armature 16. Components of injector 12 define a fluid
path for a reductant, DEF and/or urea solution through injector 12.
The reductant, DEF and/or urea solution which RDU 10 is configured
to inject into the exhaust path of a vehicle engine will be
hereinafter referred to as "reductant" for simplicity.
Fluid injector 12 is disposed in an interior carrier 18 of RDU 10,
as shown in FIG. 1. An injector shield, generally indicated at 20,
is formed by upper shield 20A and lower shield 20B, which surround
injector 12 and are coupled to carrier 18 by folding tangs of a
flange 22 of lower shield 20B over shelf features of carrier 18 and
upper shield 20A. As a result, shield 20 and carrier 18 are fixed
with respect to injector 12.
An inlet cup structure of RDU 10, generally indicated at 24 in FIG.
1, includes a cup 26 and a fluid supply tube 28 integrally formed
with cup 26. Fluid supply tube 28 is in communication with a source
of a reductant (not shown) that is fed into a fluid inlet 30 of
injector 12 for ejection from a fluid outlet 32 thereof and into
the exhaust stream of a vehicle engine (not shown). Fluid inlet 30
of injector 12 is in fluid communication with fluid supply tube 28.
Fluid outlet 32 is fluidly connected with a flange outlet 34 of an
exhaust flange 36 that is coupled directly with an end of lower
shield 20B of RDU 10.
Injector 12 includes an injector body structure in which the
components of injector 12 are disposed. The injector body structure
includes a first injector body portion 38 in which coil 14 and
armature 16 are disposed, and a valve body portion 40 in which a
valve assembly of injector 12 is at least partly disposed. First
injector body portion 38 and valve body portion 40 are fixedly
connected, either directly or indirectly, to each other.
Referring to FIGS. 1-3, fluid injector 12 includes a tube member 42
which is at least partly disposed within first injector body
portion 38. The outer surface of tube member 42 contacts the inner
surface of first injector body portion 38. An open end of tube
member 42 is disposed within cup 26 and is in fluid communication
with fluid supply tube 28. An O-ring 44 is disposed within cup 26,
between an inner surface thereof and the outer surface of tube
member 42, proximal to the open end of tube member 42. O-ring 44
serves to ensure that reductant exiting fluid supply tube 28 passes
into the open end of tube member 42 of injector 12.
The actuator unit of fluid injector 12 further includes a pole
piece 46 which is fixedly disposed within first injector body
portion 38. Coil 14 at least partly surrounds pole piece 46 and
armature 16. Pole piece 46 is disposed upstream of armature 16
within injector 12. Pole piece 46 includes a central bore defined
axially therethrough.
Armature 16 includes a U-shaped section which defines a pocket in
which at least part of a spring 50 is disposed. Spring 50, which is
part of the actuator unit, biases movable armature 16 so that
armature 16 is spaced apart from pole piece 46 when no current is
passed through coil 14. Spring 50 partly extends within the central
bore of pole piece 46. An end of spring 50 which extends within
pole piece 46 contacts a spring adjustment tube 52. Spring
adjustment tube 52 is at least partly disposed within the central
bore of pole piece 46, upstream (relative to a direction of flow of
reductant through injector 12) of spring 50. Spring adjustment tube
52 includes a bore defined axially therethrough. The throughbore of
spring adjustment tube 52 partly defines the fluid path for
reductant in fluid injector 12, and defines the only fluid path for
reductant through pole piece 46. Due to its engagement with spring
50, spring adjustment tube 52 is used to calibrate the dynamic flow
of reductant through fluid injector 12.
Armature 16 further includes one or more channels 60 (FIGS. 1 and
2) defined through the armature 16 from an interior of the pocket
to an upstream end portion of pin member 58. Channels 60 may be
equally spaced about armature 16. In an example embodiment,
armature 16 includes a single channel which is defined entirely
around the base of the pocket formed by pocket wall 16A. Channel(s)
60 allows reductant to flow from the pocket of armature 16 to the
space around the upstream end of pin member 58. The pocket of
armature 16 and the channel(s) 60 together partly define the
reductant fluid path of the fluid injector 12 and define the only
part of the fluid path passing through or around armature 16.
Referring to FIGS. 1, 2 and 5, the valve assembly of injector 12
includes a seal member 54 and a seat 56. Seal member 54 is
connected to armature 16 via a pin member 58, which is disposed
between seal member 54 and the downstream end of armature 16. Seal
member 54, pin member 58 and armature 16 may combine to form an
armature assembly. When coil 14 is energized, coil 14 generates an
electromagnetic force acting on armature 16 which overcomes the
bias force from spring 50 and causes armature 16 to move towards
pole piece 46, which correspondingly moves pin member 58 so that
seal member 54 is lifted off of, and disengages from, seat 56,
moving the armature assembly to an open position and thus
permitting reductant to pass through fluid outlet 32 to flange
outlet 34 and into the exhaust path of the vehicle engine. When
coil 14 is de-energized, the electromagnetic force dissipates and
spring 50 biases armature 16 so that armature 16 is moved away from
pole piece 46, resulting in seal member 54 sealingly engaging with
seat 56, changing the armature assembly back to a closed position.
With the armature assembly in the closed position, reductant is
prevented from flowing through seat 56 and flange outlet 34 and
into the exhaust path of the vehicle engine.
As mentioned above, RDU 10 forms part of a non-purge SCR exhaust
aftertreatment system. As a result, reductant remains in fluid
injector 12 following the vehicle engine being turned off. In
example embodiments, fluid injector 12 is configured so that the
amount of reductant in fluid injector 12 is reduced. In other
words, the total volume of the fluid path for reductant through
fluid injector 12 is reduced. By having less space for reductant in
injector 12, the amount of reductant in RDU 10 that may potentially
freeze is reduced, thereby reducing the susceptibility of injector
12 being damaged by expansion forces from frozen reductant.
In order to reduce the volume of the reductant fluid path in fluid
injector 12, the thickness of valve body portion 40 is increased.
In addition, pin member 58 is constructed as a solid element such
that reductant flows around the outer surface of pin member 58,
instead of therethrough. The spacing between the outer surface of
pin 58 and the inner surface of valve body portion 40, which partly
defines the fluid path for reductant through injector 12, is
narrowed. This narrowed portion of the fluid path is the only fluid
path for reductant between armature 16 and seat 56 in fluid
injector 12. The narrowed fluid path between pin 58 and valve body
portion 40 provides a sufficient reductant flow rate through fluid
injector 12 for performing reductant injection during normal
operation of RDU 10 while at the same time maintaining a relatively
small volume of reductant within injector 12 so as to lessen the
risk of injector 12 being damage from the reductant therein
freezing.
Further, the diameter of the pocket of armature 16, in which spring
50 is at least partly disposed, is reduced, which allows for the
thickness of pocket wall 16A of armature 16 to be increased. In an
example embodiment, the thickness of pocket wall 16A is between 45%
and 75% of the diameter of pocket, such as about 60%. The increase
in thickness of pocket wall 16A, as well as the increased thickness
of valve body portion 40 and pin member 50 being a solid pin,
result in the components of injector 12 being strengthened and thus
more resistant to reductant freezing forces.
Still further, the bore of spring adjustment tube 52 is sized for
reducing the volume of the reductant fluid path in injector 12. In
an example embodiment, the diameter of the bore of spring
adjustment tube 52 is between 12% and 22% of the outer diameter of
pole piece 46, and particularly between 16% and 19% thereof.
FIG. 3 illustrates an upstream portion of injector 12. Tube member
42 extends at least partly though injector 12. The reductant fluid
path through injector 12 passes through tube member 42. Injector 12
includes a filter 204 disposed within tube member 42 proximal to
the open end thereof. Filter 204 is a structurally rigid, sintered
metal filter, such as a stainless steel material, in order to
better withstand expansion forces from reductant freezing. Filter
204 may have a supporting outer structure for added strength. Best
seen in FIG. 3, filter 204 is disposed within a cap member 206. Cap
member 206 is largely cylindrically shaped having a sidewall 206A
extending circumferentially and defining an inner volume sized for
receiving filter 204 therein. Cap member 206 is dimensioned to fit
within tube member 42, and particularly so that the outer surface
of sidewall 206A of cap member 206 contacts the inner surface of
tube member 42. Cap member 206 further includes annular members
206B disposed along the axial ends of cap member 206 and extend
radially inwardly from sidewall 206A. Annular members 206B serve to
maintain filter 204 within cap member 206 in a fixed position. Cap
member 206 is constructed of metal or like compositions.
Injector 12 further includes a retaining ring 207 which is disposed
in tube member 42 upstream of, and in contact with, cap member 206,
as shown in FIGS. 1-3. Retainer ring 207 is fixed to tube member 42
along an inner surface thereof. Retainer ring 207 being fixed in
position along tube member 42 serves to maintain downstream
components of injector 12 in fixed positions within first injector
body portion 38. In an example embodiment, retainer ring 207 is
welded along the inner surface of tube member 42. Such weld
connection is formed along an entire circumference of the upper
edge of retainer ring 207. It is understood, however, that other
connection mechanisms may be utilized for fixing retainer ring 207
to tube member 42.
Referring to FIGS. 1-4, injector 12 further includes a volume
reduction member 208 which serves to further reduce the volume of
the reductant fluid path within injector 12. Reduction member 208
is largely cylindrical in shape, as shown in FIG. 4, having a top
(upstream) end and a bottom (downstream) end. In an embodiment,
volume reduction member 208 is constructed from a metal, such as
stainless steel. It is understood, though, that volume reduction
member 208 may be formed from other metals or metal compositions.
The outer surface of volume reduction member 208 is sized to
contact the inner surface of tube member 42.
Volume reduction member 208 further includes a bore 208A (FIGS. 2
and 3) defined in the axial direction through volume rejection
member 208, from one axial (top) end to the other axial (bottom)
end. Bore 208A is located along the longitudinal axis of volume
reduction member 208 and itself forms part of the fluid path for
passing reductant through injector 12. Bore 208A forms the only
fluid path for passing reductant through or around volume reduction
member 208. In an example embodiment, the diameter of bore 208A is
between 12% and 20% of the outer diameter of volume reduction
member 208, such as about 16%. Because volume reduction member 208
extends radially to the inner surface of tube member 42, and
because the diameter of bore 208A is small relative to the outer
diameter of volume reduction member 208, volume reduction member
208 reduces the space or volume in which reductant may reside
within injector 12, thereby reducing the volume of the fluid path
of reductant therein. Volume reduction member 208 further assists
in retaining spring adjustment tube 52 in position within injector
12 such that pin adjustment tube 52 maintains a desired force on
spring 50 so as to prevent a loss of calibration. Specifically,
retainer ring 207 maintains the position of filter 204 and
corresponding cap member 206, which maintain the position of volume
reduction member 208, which maintains the position of spring
adjustment member 52.
With reference to FIGS. 1-4, fluid injector 12 further includes a
volume compensation member 210 which is disposed between the bottom
(downstream) end of volume reduction member 208 and the top of pole
piece 46. Volume compensation member 210 is constructed from
elastic material and serves to occupy the space between volume
reduction member 208 and pole piece 46 so as to further lessen the
volume of the reductant fluid path in injector 12. Volume
compensation member 210 may be in a compressed state in injector 12
when assembled, and contact the volume reduction member 208, pole
piece 46, the inner surface of tube member 42 and the outer surface
of spring adjustment member 52.
FIG. 5 illustrates a downstream end portion of fluid injector 12.
As can be seen, seat 56 includes a bore defined axially through
seat 56. In an example embodiment, the length of the throughbore of
seat 56 is reduced so as to further reduce the volume of the
reductant fluid path through seat 56, and particularly the sac
volume below the sealing band of seat 56 which engages with seal
member 54.
According to an example embodiment, fluid injector 12 includes a
plurality of orifice discs 212 disposed in a stacked arrangement.
The orifice disc stack is disposed against the downstream end of
seat 56. In the example embodiment illustrated in FIG. 5, the disc
stack includes a first disc 212A having one or more orifices that
are configured for providing the desired spray pattern of reductant
exiting injector 12. It is understood that the dimension and
locations of the orifices of first disc 212A may vary and be
dependent upon the reductant dosing requirements of the particular
vehicle engine. The disc stack further includes a second disc 212B
which is disposed downstream of first disc 212A and includes
orifices through which the reductant spray passes. Second disc 212B
has a larger thickness than the thickness of first disc 212A and
being disposed against first disc 212A, and supports first disc
212A so as to prevent the thinner first disc 212A from deforming
due to expansion forces from frozen reductant upstream of first
disc 212A.
As discussed above, fluid injector 12, and particularly the
components thereof, are configured to reduce the volume of the
reductant fluid path in injector 12. In example embodiments, the
ratio of the volume of the fluid path in fluid injector 12 to a
volume of the components of injector 12 (including but not
necessarily limited to coil 14, armature 16, pole piece 46, spring
adjustment tube 52, volume reduction member 208, volume
compensation member 210, filter 204, retaining ring 207, spring 50,
pin member 58, seal member 54, seat 56, first injector body portion
20A and valve body portion 40) is between 0.08 and 0.30, and
particularly between 0.12 and 0.20, such as about 0.15. These
volume amounts are calculated between orthogonal planes relative to
the longitudinal axis of fluid injector 12--from a first plane
along the open end of tube member 42 (i.e., fluid inlet 30) and a
second plane along the lowermost (downstream) surface of second
disc 212B (i.e., fluid outlet 32). It is understood that the
particular ratio of volume of the reductant path to injector
component volume within fluid injector 12 may vary depending upon a
number of cost and performance related factors, and may be any
value between about 0.08 and about 0.30. Providing a fluid injector
having a reduced ratio of reductant fluid path volume to injector
component volume to fall within the above range advantageously
results in less reductant in injector 12 which reduces the
susceptibility of RDU 10 being damaged if the reductant in injector
12 freezes.
In another example embodiment, shown in FIGS. 6-8, fluid injector
12 includes a volume reduction member 308 which has many of the
characteristics of volume reduction member 208 discussed above with
respect to FIGS. 1-5. Similar to volume reduction member 208,
volume reduction member 308 is constructed from stainless steel or
like composition, is disposed in tube member 42 of fluid injector
12 between volume compensation member 210 and filter 204. However,
volume reduction member 308 includes a first portion 308A and a
second portion 308B. As shown in FIG. 7, each of first portion 308A
and second portion 308B has a cylindrical shape, with the outer
diameter of first portion 308A being less than the outer diameter
of second portion 308B. The outer diameter of first portion 308A is
less than the diameter of second portion 308B by the thickness of
sidewall 306A of cap member 306, as will be explained in greater
detail below. Volume reduction member 308 includes top (upstream)
and bottom (downstream) end portions which form the axial ends of
first portion 308A and second portion 308B, respectively. The outer
surface of second portion 308B is sized to contact the inner
surface of tube member 42.
As mentioned, the outer diameter of first portion 308A of volume
reduction member 308 is less than the outer diameter of second
portion 308B thereof. As shown in FIGS. 6-8, volume reduction
member 308 includes an angled annular surface or skirt 308D, which
extends in the axial direction between the outer surface of first
portion 308A and the outer surface of second portion 308B and
serves as the physical interface therebetween. The angle of angled
surface 308D, relative to the longitudinal axis of volume reduction
member 308 and/or injector 12, is an acute angle. Alternatively,
the angle of angled surface 308D is orthogonal to the longitudinal
axis of volume reduction member 308 and/or injector 12.
Volume reduction member 308 further includes a bore 308C defined in
the axial direction through volume rejection member 308, from one
axial (top) end to the other axial (bottom) end. Bore 308C is
located along the longitudinal axis of volume reduction member 308
and itself forms part of the reductant fluid path for passing
reductant through injector 12, and the only reductant fluid path
through or around volume reduction member 308. In an example
embodiment, the diameter of the bore 308C is between 12% and 20% of
the outer diameter of volume reduction member 308, such as about
16%. Because volume reduction member 308 extends to the inner
surface of tube member 42 and because the diameter of bore 308C is
relatively small relative to the outer diameter of volume reduction
member 308, volume reduction member 308 occupies a volume within
injector 12 which reduces the space or volume of the reductant
fluid path through injector 12, thereby reducing the amount of
reductant in injector 12 that could freeze and potentially damage
injector 12.
Cap member 306 includes a number of the same characteristics of cap
member 206 described above with respect to FIGS. 1-5. As shown in
FIG. 7, cap member 306 is largely cylindrically shaped having a
sidewall 306A extending circumferentially and defining an inner
volume sized for receiving filter 204 therein. Cap member 306 is
dimensioned to fit within tube member 42, and particularly so that
the outer surface of sidewall 306A of cap member 306 contacts the
inner surface of tube member 42. Cap member 306 further includes an
annular member 306B disposed along the axial (upstream) end of cap
member 306 and extending radially inwardly from sidewall 306A.
Annular member 306B serves to maintain filter 204 within cap member
306 in a fixed position. Like cap member 206, cap member 306 is
constructed of metal or like compositions and provides structural
support to filter 204.
In example embodiments, cap member 306 is engaged with and secured
to volume reduction member 308. In this way, filter 204, cap member
306 and volume reduction member 308 form a single, unitary and
integrated component, as shown in FIG. 8. Having a single, unitary
component formed from filter 204, cap member 306 and volume
reduction member 308 advantageously allows for a simpler and less
complex process for assembling injector 12 during manufacture
thereof.
In the example embodiments, cap member 306 fits over and engages
with or otherwise attaches to at least a part of first portion 308A
of volume reduction member 308, as shown in FIGS. 6 and 8. In one
example embodiment, cap member 306 forms a press fit engagement
with first portion 308A. In another example embodiment, cap member
306 is welded to first portion 308A, such as a fillet weld between
bottom surface 306C of cap member 306 and the radially outer
surface of first portion 308A. In each such embodiment, the angled
surface 308D provides sufficient spacing for securing cap member
306 to first portion 308A. It is understood that cap member 306 may
be secured to first portion 308A of volume reduction member 308 via
other mechanisms.
With cap member 306 fitting over first portion 308A of volume
reduction member 308, the outer diameter of sidewall 306A is the
same or nearly the same as the outer diameter of second portion
308A. See FIGS. 6 and 8.
As discussed above, volume reduction member 308 is constructed from
metal, such as stainless steel, according to an example embodiment.
In another example embodiment, a part of second portion 308B is
constructed from plastic or like compositions. Specifically, as
illustrated in FIGS. 9-11, first portion 308A and a first part
308B-1 of second portion 308B are formed as a single metal member,
and a second part 308B-2 of second portion 308B is plastic
overmolded around the first part thereof. FIG. 11 shows the metal
first portion 308A and first part 308B-1 of second portion 308B.
First part 308B-1 of second portion 308B includes intermediate
section 308B-3 which extends away from first portion 308A in an
axial (downstream) direction, and distal section 308B-4 which is
attached to intermediate section 308B-3 and extends in the axial
(downstream) direction therefrom, as shown in FIG. 10. Distal
section 308B-4 extends in a radial direction further from a
longitudinal axis of volume reduction member 308 (and/or injector
12) than the radial extension of intermediate section 308B-3 so as
to form a ledge. Second part 308B-2 of second portion 308B, made of
overmolded plastic or other like compositions, is formed around the
ledge formed by intermediate section 308B-3 and distal section
308B-4 so as to form volume reduction member 308 as a single,
unitary and integrated component. As discussed above, volume
reduction member 308 is connected to cap member 306 so as to result
in volume reduction member 308, filter 204 and cap member 306
forming a single assembly component for use in assembling injector
12.
During assembly of injector 12, the single assembly component
(filter 204, cap member 306 and volume reduction member 308) is
inserted within tube member 42 under pressure while contacting
volume compensator 212. Following insertion and while still under
pressure, cap member 306 is welded to tube member 42 all along the
intersection thereof along the top portion of tube member 42. In an
embodiment, the weld connection is a fillet weld.
FIG. 12 illustrates fluid injector 12 according to another example
embodiment. In this embodiment, fluid injector 12 includes filter
204 and cap member 306 in which filter 204 is disposed, as
described above. In addition, fluid injector 12 includes
calibration filter tube 402 and volume reduction member 408.
Calibration filter tube 402 includes a bore 402A which is axially
defined through calibration filter tube 402. At one (upstream) end
of calibration filter tube 402, bore 402A is in fluid communication
with filter 204 for receiving reductant therefrom. At the other
(downstream) end of calibration filter tube 402, bore 402A provides
reductant to armature 16. In this way, calibration filter tube 402
forms part of the fluid path for reductant through fluid injector
12, and forms the only such fluid path from filter 204 to armature
16. With the diameter of bore 402A of calibration filter tube 402
being small relative to the inner diameter of tube member 42, the
volume of the fluid path for reductant through injector 12 is
reduced so as to lessen the adverse impact of reductant freezing
therein.
As shown in FIGS. 12-14, calibration filter tube 402 further
includes first end portion 402B which is disposed at least partly
within cap member 306 and contacts filter 204. First end portion
402B is largely disc-shaped, having a sidewall 402C which contacts
the inner surface of sidewall 306A of cap member 306. In an example
embodiment, first end portion 402B of calibration fluid member 402
is attached to cap member 306 so that cap member 306, filter 204
and calibration filter tube 402 form a single, unitary and
integrated subassembly component for facilitating simplified
assembly of fluid injector 12. In one example embodiment, cap
member 306 engages with first end portion 402B, and particularly
forms a press fit engagement therewith. In another example
embodiment, cap member 306 is welded to first end portion 402B,
such as a fillet weld connection between the axial end of sidewall
306A of cap member 306 and the outer surface of sidewall 402C of
first portion 402A. It is understood that, alternatively or
additionally, cap member 306 may be secured to first end portion
402B of calibration filter tube 402 using other techniques.
Calibration filter tube 402 further includes elongated second
portion 402D which extends in an axial direction from first portion
402A, as shown in FIGS. 12-14. Second portion 402D is sized to
extend into pole piece 46 so that a second end 402E, opposite first
end portion 402B, engages with spring 50 (FIG. 12). Second portion
402D is largely cylindrically shaped, with bore 402A disposed
therein. Calibration filter tube 402 further includes annular tab
402F which extends radially outwardly from the outer surface of
second portion 402D. Tab 402F extends slightly outwardly from the
outer surface of, and is positioned along, second portion 402D of
calibration filter tube 402 so as to contact the inner surface of
pole piece 46 defining the central bore thereof. This contact
between tab 402F and the central bore of pole piece 46 results in
calibration filter tube 402 forming a press fit attachment with
pole piece 46.
As mentioned, second end 402E of calibration filter tube 402
contacts and engages with spring 50. Due to the engagement between
calibration filter tube 402 and spring 50, and the engagement
between armature 16 and spring 50, calibration filter tube 402 is
used to calibrate the dynamic flow of reductant through fluid
injector 12. Specifically, with cap member 306, filter 204 and
calibration filter tube 402 being formed as a single, unitary and
integrated subassembly component, positioning calibration filter
tube 402 in the desired position within tube member 42, prior to
welding cap member 306 thereto, is simplified for providing the
desired calibrated force for spring 50.
Calibration filter tube 402 is formed from a metal composition,
such as stainless steel.
With continued reference to FIGS. 12-14, injector 12 further
includes volume reduction member 408 which is disposed around
second portion 402D of calibration filter tube 402. Volume
reduction member 408 has a cylindrical shape, with a central bore
defined axially through volume reduction member 408. The central
bore of volume reduction member 408 is sized for receiving
calibration filter tube 402 therein. As shown in FIG. 12, the outer
radial surface of volume reduction member 408 contacts the inner
surface of tube member 42. One axial (upstream) end of volume
reduction member 408 is disposed adjacent and contacts first end
portion 402B of calibration filter tube 42, and the other axial
(downstream) end of volume reduction member 408 is disposed against
and contacts the upstream end of pole piece 46. In this way, volume
reduction member 408 occupies the space between second portion 402D
of calibration filter tube 402 and tube member 42 that is upstream
of pole piece 46 and downstream of first end portion 402B of
calibration filter tube 402. In an example embodiment, volume
reduction member 408 is attached to calibration filter tube 402
such that volume reduction member 408 forms the single, unitary and
integrated subassembly component with cap member 306, filter 204
and calibration filter tube 402.
In an example embodiment, volume reduction member 408 is
constructed from a resilient and compressible material, and is
compressible in at least the axial direction along fluid injector
12. Volume reduction member 408 being compressible in the axial
direction allows for the single assembly component (cap member 306,
filter 204 and calibration filter tube 402) to be adjustably
positioned within tube member 42 relative to pole piece 46 so that
the opening and closing force of the valve assembly of fluid
injector 12 may be easily calibrated as desired. In one embodiment,
volume reduction member 408 is constructed from closed cell foam.
It is understood, though, that volume reduction member 408 may be
constructed from other compressible material. If constructed from
closed cell foam, volume reduction member 408 is compressible in
both axial (longitudinal) and radial (lateral) directions. In an
example embodiment, volume reduction member 408 is in a compressed
state in fluid injector 12.
FIGS. 15-17 illustrate fluid injector 12 according to another
example embodiment. In this embodiment, fluid injector 12 includes
filter 204 and cap member 306 in which filter 204 is disposed, as
described above. In addition, fluid injector 12 includes
calibration filter tube 502. Calibration filter tube 502 has many
features of calibration filter tube 402 described above with
respect to FIGS. 12-14.
Calibration filter tube 502 includes a bore 502A which is axially
defined through calibration filter tube 502. At one (upstream) end
of calibration filter tube 502, bore 502A is in fluid communication
with filter 204 for receiving reductant therefrom. At the other
(downstream) end of calibration filter tube 502, bore 502A provides
reductant to armature 16. In this way, calibration filter tube 502
forms part of the fluid path for reductant through fluid injector
12, and forms the only such fluid path from filter 204 to armature
16. With the diameter of bore 502A of calibration filter tube 502
being small relative to the inner diameter of tube member 42, the
volume of the fluid path for reductant through injector 12 is
reduced so as to lessen the adverse impact of reductant freezing
therein.
As shown in FIGS. 15-17, calibration filter tube 502 further
includes first end portion 502B which is disposed at least partly
within cap member 306 and contacts filter 204. First end portion
502B is largely disc-shaped, having a sidewall 502C which contacts
the inner surface of sidewall 306A of cap member 306. In an example
embodiment, first end portion 502B of calibration fluid member 502
is attached to cap member 306 so that cap member 306, filter 204
and calibration filter tube 502 form a single, unitary and
integrated subassembly component for facilitating simplified
assembly of fluid injector 12. In one example embodiment, cap
member 306 engages with first end portion 502B, and particularly
forms a press fit engagement therewith. In another example
embodiment, cap member 306 is welded to first end portion 502B,
such as a fillet weld connection between the axial end of sidewall
306A of cap member 306 and the outer surface of sidewall 502C of
first portion 502B. It is understood that, additionally or
alternatively, cap member 306 may be secured to first end portion
502B of calibration filter tube 502 using other techniques.
Calibration filter tube 502 further includes an elongated second
portion 502D which extends in an axial direction from first portion
502A, and an elongated third portion 502E which extends in the
axial direction from second portion 502D, as shown in FIGS. 15-17.
Third portion 502E is sized to extend into pole piece 46 so that a
second end 502F of calibration filter tube 502, opposite first end
portion 502B, engages with spring 50 (FIG. 12). Second portion 502D
and third portion 502E are largely cylindrically shaped, with bore
502A disposed therein.
In an example embodiment, the outer diameter of second portion 502D
is larger than the outer diameter of third portion 502E. The outer
diameter of third portion 502E is sized for being received in the
central bore of pole piece 46.
Calibration filter tube 502 further includes annular tab 502G (FIG.
17) which extends radially outwardly from the outer surface of
third portion 502E. Tab 502G extends slightly outwardly from the
outer surface of, and is axially positioned along, third portion
502E of calibration filter tube 502 so as to contact the inner
surface of pole piece 46 defining the central bore thereof. This
contact between tab 502G and the central bore of pole piece 46
results in calibration filter tube 502 forming a press fit
engagement with pole piece 46.
Calibration filter tube 502 is formed from a metal composition,
such as stainless steel.
As mentioned, second end 502F of calibration filter tube 502
contacts and engages with spring 50. Due to the engagement between
calibration filter tube 502 and spring 50, and the engagement
between spring 50 and armature 16, calibration filter tube 502 is
used to calibrate the dynamic flow of reductant through fluid
injector 12. Specifically, with cap member 306, filter 204 and
calibration filter tube 502 being formed as a single, unitary and
integrated subassembly component, positioning of calibration filter
tube 502 in the desired position within tube member 42, prior to
welding cap member 306 thereto, is simplified for providing the
desired calibrated force for spring 50 for setting the opposed
opening and closing force for the valve assembly of fluid injector
12.
With continued reference to FIGS. 15-17, injector 12 further
includes volume reduction member 508 which is disposed around
second portion 502D of calibration filter tube 502. Volume
reduction member 508 has a generally cylindrical shape, with a
central bore defined axially through volume reduction member 508.
The central bore of volume reduction member 508 is sized for
receiving second portion 502D of calibration filter tube 502
therein. As shown in FIG. 12, the outer radial surface of volume
reduction member 508 contacts the inner surface of tube member 42.
One axial (upstream) end of volume reduction member 508 is disposed
adjacent and contacts first end portion 502B of calibration filter
tube 42, and the other axial (downstream) end of volume reduction
member 508 is disposed against and contacts the upstream end of
pole piece 46. In this way, volume reduction member 508 occupies
the space between second portion 502D of calibration filter tube
502 and tube member 42 that is upstream of pole piece 46 and
downstream of first end portion 502B of calibration filter tube
502.
In an example embodiment, volume reduction member 508 is
constructed from compressible material, such as being compressible
in at least the axial direction along fluid injector 12. Volume
reduction member 508 being compressible in at least the axial
direction allows for the single assembly component (cap member 306,
filter 204 and calibration filter tube 502) to be adjustably
positioned within tube member 42 relative to pole piece 46 so that
the valve assembly of fluid injector 12 may be calibrated as
desired. In an example embodiment, volume reduction member 508 is
in a compressed state in fluid injector 12.
As shown in FIGS. 15-17, volume reduction member 508 includes a
sidewall 508A which extends between two axial ends. A downstream
axial end wall 508B of volume reduction member 508 extends radially
inwardly from sidewall 508A and contacts the outer surface of third
portion 502E of calibration filter tube 502. The upstream axial end
of volume reduction member 508 may be open and contact a downstream
surface of first portion 502B of calibration filter tube 502.
Sidewall 508A of volume reduction member 508 undulates in an axial
direction, as shown in FIGS. 15-17, alternating between sidewall
peaks and valleys in a wave-like pattern relative to a longitudinal
axis of volume reduction member 508 and/or injector 12. Having an
undulating sidewall 508A facilitates sidewall 508A being
compressible or otherwise partly collapsible in both axial
(longitudinal) and radial (lateral) directions. In an example
embodiment, volume reduction member 508 is constructed from a
compressible, resilient material, such as a rubber composition or
other like material. Volume reduction member 508 may be in a
compressed state within fluid injector 12.
FIG. 18 depicts fluid injector 12 according to another example
embodiment. In this embodiment, fluid injector 12 includes many of
the components of example embodiments described above, including
but not limited to armature 16, pole piece 40, pin member 58 and
spring 50, and such components have the same corresponding
reference numbers. In addition, fluid injector 12 includes a spacer
member 180 disposed in proximity to the valve assembly of fluid
injector 12. In the example embodiment, spacer member 180 has a
ring and/or annular shape with a polygonal shaped cross-section,
such as a square or rectangular shaped cross-section, but it is
understood that spacer member 180 may have other shapes and/or be
formed from a number of elements which combine to form the ring
and/or annular shape. As shown in FIGS. 18 and 19, valve body
member 40 includes a shoulder or ledge 40A which extends radially
in a direction that is orthogonal to a longitudinal axis of fluid
injector 12. Shoulder 40A provides a transition between distinct
radial dimensions of open spaces within fluid injector 12, with one
such open space having pin member 58 disposed therein and a second
open space having armature 16 and pole piece 40 disposed therein.
Spacer member 180 is disposed on and above shoulder 40A, radially
between an inner surface of valve body portion 40 and an outer
surface of an upstream end of pin member 180. Further, spacer
member 180 is disposed between shoulder 40A and a downstream (i.e.,
lower, as viewed in FIGS. 18 and 19) end portion 16B of armature
16. Spacer member 180 occupies a volume in an open space in a fluid
flow path in fluid injector 12 through which fluid, such as a
reductant, would otherwise occupy. By occupying a space in fluid
injector 12 which would otherwise be occupied by reductant, a
reduced amount of reductant may be disposed in fluid injector 12,
thereby lessening an amount of reductant which may freeze and
damage components of fluid injector 12.
In an example embodiment, spacer member 180 is constructed from a
compressible, resilient material, such as a rubber composition and
closed cell foam. In this way, expansion forces from freezing
and/or frozen reductant located in or around armature 16 cause
spacer member 180 to be compressed, thereby allowing the
expanding/expanded reductant to occupy the space occupied by spacer
member 180 absent its compression. This provides available space
for the reductant to expand when freezing so that reductant
expansion forces are not directed to other components of fluid
injector 12. When the frozen reductant melts, spacer member 180
resiliently expands and returns to its largely uncompressed
state.
FIGS. 20 and 21 illustrate a spacer member 180' having the same
resilient, compressible characteristics as described above with
respect to spacer member 180. In addition, spacer member 180' has a
circular cross-sectional shape. It is understood that,
alternatively, spacer member 180' may have an oblong or oval shaped
cross-section.
FIGS. 20 and 21 illustrate that an inner wall 40B of valve body
portion 40 may be shaped and/or otherwise have a contour for
receiving spacer member 180' therein.
Use of spacer members 180, 180' results in a compression seal to
reduce fluid volume in fluid injector 12, compressing as reductant
freezes and expanding as frozen reductant melts, preventing
component displacement of other components of injector 12 from
freezing forces from the reductant. This is achieved with spacer
member 180, 180' being compressible which can expand and contract
at varying temperatures to ensure the space in fluid injector 12
for holding reductant is reduced or minimized. Spacer member 180,
180' reduces the volume of the reductant fluid path in injector 12
while being compressible so as to absorb reductant freezing forces,
thereby resulting in a more robust fluid injector 12. The
compressible material of spacer member 180, 180' is such that the
material will expand and contract at various temperatures so as to
ensure that the available space for reductant in fluid injector 12
is reduced. Spacer member 180, 180' absorbs freezing forces and
compresses as a result, thereby reducing freezing forces directed
to other components and interfaces within fluid injector 12.
FIG. 22 illustrates an aspect of fluid injector 12 of FIG. 18 in
accordance with another example embodiment. Specifically, fluid
injector 12 includes filter 204 and cap member 306 in which filter
204 is disposed, as described above. Fluid injector 12 of FIG. 18
further includes a calibration filter tube 502. Calibration filter
tube 502 includes many or all of the features of calibration filter
tube 402 described above with respect to FIGS. 12-14. For example,
calibration filter tube 502 includes a disc-shaped first end
portion 502B, similar to first end portion 402B, and a second end
502E. First end portion 502B includes a sidewall 502C, similar to
sidewall 402C. Elongated second portion 502D extends between first
end portion 502B and second end 502E through which bore 502A
extends. Annular tab 502F is disposed in a central region of
elongated second portion 502D. Further, unlike calibration filter
402, calibration filter tube 502 includes a plurality of holes 502G
which are disposed at least along an upstream (top, relative to
FIG. 22) portion of elongated second portion 502D which is adjacent
volume reduction member 408. Each hole 502G extends between
central, axial bore 502A and an outer surface of elongated second
portion 502D. In this way, fluid/reductant is able to pass between
bore 502A and a space along an outer surface of elongated second
portion 502D.
Fluid injector 12 of FIG. 18 further includes volume reduction
member 408 as described above with respect to FIGS. 12-14. Volume
reduction member 408 is constructed from a resilient and
compressible material, and is resiliently compressible in axial and
radial directions along fluid injector 12. Volume reduction member
408 being compressible in the axial direction allows for the single
assembly component (cap member 306, filter 204 and calibration
filter tube 502) to be adjustably positioned within tube member 42
relative to pole piece 46 so that the opening and closing force of
the valve assembly of fluid injector 12 may be easily calibrated as
desired. In one embodiment, volume reduction member 408 is
constructed from closed cell foam. It is understood, though, that
volume reduction member 408 may be constructed from other
resilient, compressible material. In an example embodiment, volume
reduction member 408 is in a partly compressed state in fluid
injector 12.
Freezing reductant that is disposed within bore 502A of calibration
filter tube 502 is allowed to expand through holes 502G so that
calibration filter tube 502 is less likely to being damaged from
expanding reductant disposed therein. With holes 502G being
adjacent volume reduction member 408, freezing reductant expanding
through holes 502G contact and compress volume reduction member 408
so as to allow for expanding (freezing) reductant to easily exit
calibration filter tube 502, thereby reducing or eliminating
freezing forces acting thereon.
The reductant flow path through fluid injector 12 may include a
fluid path from bore 502A, through holes 502G and into pocket 16A
before passing through channels 60 and along the outer surface of
pin member 58 before exiting fluid outlet 32. In this case, holes
502G of calibration filter tube 502 form part of the fluid
(reductant) path through fluid injector 12.
The example embodiments have been described herein in an
illustrative manner, and it is to be understood that the
terminology which has been used is intended to be in the nature of
words of description rather than of limitation. Obviously, many
modifications and variations of the invention are possible in light
of the above teachings. The description above is merely exemplary
in nature and, thus, variations may be made thereto without
departing from the spirit and scope of the invention as defined in
the appended claims.
* * * * *
References